Production of cellulose derivative cut staple fibers



April 22, w C O EI-AL 2,238,977

PRODUCTION OF CELLULOSE DERIVATIVE CUT STAPLE FIBERS Filed Sept. 16,1937 /=/6.4 H6. 5 F/G. 6

f/en/y A. Chi/d5 INVENTORS 7%- W SSMU ATT0%EYS Patented Apr. 22, 1941 1UNITED STATES PATENT OFFICE I PRODUCTION OF CELLULOSE DERIVATIVE CUTSTAPLE FIBERS Wallace '1. Jackson and Henry R. Childs, Kingsport, Tenn.,assignors to Eastman Kodak Company, Rochester, N. Y.

Jersey a corporation of New 11 Claims.

This invention relates to cellulose derivative cut staple fibers and tothe production thereof, and more particularly tothe production ofcrimped cut staples having an appearance closely simulating naturalwool.

This application is in part a continuation of our application, SerialNo. 114,078, filed December 3, I936.

As is well-known, synthetic filaments or fibers produced from cellulosederivatives, particularly cellulose organic derivatives such ascellulose acetate, cellulose acetate propionate, the cellulose ethersand others, have a smooth exterior surface; Natural wool fibers, on theother hand (and cotton fibers to a lesser degree) are characterized byirregularity of surface formation and cross-section and a naturalkinkiness which gives them their characteristic woolly appearance andfeel and a high degree of resiliency. This kinkiness or woolinessrenders such fibers especially well adapted for the manufacture ofvarious types of yarns and fabrics, especially those which treating thefibers externa y as distinguished from the method more fully set forthhereinafter.

are subjected to hard wear, because of the fact I that it enables themto be readily spuninto strong threads by virtue of the interlocking ofthe individual fibers. As indicated, synthetic fibers are ordinarilylacking in this natural wooliness or klnkjness and therefore, asordinarily produced, are inherently unadapted for the some uses to whichnatural wool and cotton fibers can readily ture," wool substitute," andthe like, but the fact remains that the art does not disclose, nor hasThe principal object of the present invention is to provide a process ofproducing a wholly new and improved type of cellulose derivative cutstaple fiber of irregularly rounded cross-section closely resemblingnatural wool in appearance and in its ability tobe spun into yarn andwoven into fabrics closely resembling fabrics produced from naturalwool. A further object is to provide a process whereby celluloseorganici derivative filaments, particularly those produced fromcellulose acetate may be converted into a form closely simulatingnatural wool fibers. A still further object is to provide a process ofmaking cellulose organic derivative filaments of such character as to bereadily convertible into a kinky or wool-like condition. Another andmore specific object is to provide a new type of wool substitute inwhich the individual fibers are characterized by a unique externalconfiguration and unique physical and chemical properties, particularlya high degree of resiliency and the ability to retain their resiliency,naturalluster and characteristic wool-like condition, even whensubjected to repeated scouring in hot aqueous baths. A further specificobject is to provide a new and improved type of spun yarn suitable for awide variety of purposes, including knitting, weaving and the like, andparticularly adapted for the manufacture of suitings, blankets and manyother textile materials. A still further specific object is to provide anew type of fabric characterized by the presence therein, in whole or inpart, of a new and improved type of synthetic wool staple yarn hereindescribed. Other objects will appear hereinafter.

These objects are accomplished by the following invention, which, in itsbroader aspects, comprises incorporating in the cellulose derivativeanyone, until the advent of the present invention I come forward with,synthetic staple which actually simulates natural wool and is capable ofbeing spun or woven into fabrics closely resembling fabrics producedfrom the natural product.

It is noteworthy that practically all of the methods thus far suggestedfor the production of synthetic staples had been based, either upon theprinciple of subjecting the fibers to drastic external physicalmodification, as by cutting under tension, molding and thencutting,stretching. pressing, and the like or upon the principle of solution ordope from which the'filaments are to be spun, a crimping, crinkling', orkinking agent terial at a moderately elevated temperature;

spinning the dope into filaments in the usual manner, cutting thefilaments into staplelengths and subjecting the cut staple to the actionof a non-solvent in liquid or vapor form at a temperature of about 100C. or over. The fibers even applying to fibers externally a chemicalcrimping when subjected to this rather drastic treatment,

do not; under the conditions of operation described herein, appreciablylose their characteristic luster or strength.

In the accompanying drawing, constituting part hereof, Figs. 1, 2, and 3depict three different 4 filaments (upon an enlarged scale).ofwoolelike. cut staple filaments selected at random from a batch madein accordance with our invention.

Figs. 4, 5, and 6 illustrate cross-sections of typical filaments alsoselected at random from a batch of the same type of filaments asillustrated in Figs. 1, 2,.and 3. v a

We have found that-a rather wide range of substances may be employed asthe crimping or crinkling agent in accordance with our invention. Wehave found it somewhat difiicult to define theexact physicalpropertiesof 'those compounds which we define as crimping or crinkling agents.Apparently thereis some unusual relationship between the celluloseorganic derivatives and certain compounds which may be incorporatedtherein which causes crinkling, upon subsequent treatment of the fibersas herein defined. Obviously the agent must cause crinkling but not withany substantial delustering or weakmerely aconditioning component forthe cellulose organic derivative. -To be considered a crinkling agentwithin the scope of this application, the agent must be capable ofproducing greater than about 10 crimps per inch in the cellulose organicderivative fiber as we do not regard a fiber with a lesser number ofcrimps per inch as simulating wool in appearance. Among the manycompounds which we have found eminently satisfactory as crinkling agentsare high boiling plasticizers such as glycerol trlpropionate,

glycerol tributyrate, dimethyl phthalate, dibutyl phthalate, dibutyl vtartrate and mixtures of these plasticizers, such forexample, asamixture of orthoand paratoluene ethyl sulfonamides, sold under thetrade'name Santicizer 8. Ethyl phthalyl ethyl glycollate, sold, underthe trade compounds, we have found. that methyl cellosolve (themonomethyl ether of ethylene glycol) and carbitol acetate (the acetateof diethylene glycol monoethyl ether) may be used.

So far as the production of the yarn itself is concerned, itniay be madeaccording to standard acetate yarn practice. Fbr example, we may employa process broadlysimilar to that disclosed .in the Stone U. 8. Patent2,000,047 or the Stone U. 8. Patent 2,000,048. In such a process acellulose acetate spinning dope of suitable composition may be preparedin accordance with known technique. Preferably the dope is a triplefiltered bright luster dope to which a crimping agent has been added inan amount corresponding to 1 to 15% on the dry weight of the celluloseacetate. The dope is then extruded through a spinneret having the typeof extrusion orifices to give filaments of the proper denier. Forexample, if a 10 denier filament is desired, a spinneret havingextrusion orifices of .1 mm. in diameter will be suitable. The dopepasses through a candle filter heated to about 69 C. and is extrudeddownwardly, the filaments being carried through a body of evaporativemedium such as air which passes countercurrently to the filaments andupwardly through the spinning cabinet. The air temperature may vary asdesired, an appropriate temperature in the cabinet being represented byan inlet temperature of somewhere in the neighborhood of 100 to 110 C.and an outlet temperature of about 78 C. The air may pass through thecabinet, which may range in length from 10 to 20 feet in height, the airpassing out of the cabinet at a point somewhere about Y; of the way fromthe top as disclosed in the above-mentioned Stone patents, at a speedcorresponding to about. 23 cubic feet per minute.

Due to'the'fact that the agents which we prefer to employ in ourinvention have relatively high boiling points, that is, above 100 0.,the yarn emerges from the spinning cabinet carrying the name SanticizerE45," has also been found to be satisfactory. While any of. theaforementioned plasticizers maybe successfully employed in connectionwith cellulose acetate and other cellulose organic derivative filaments,we prefer the use of glycerol trlbutyrate as this compound appears to beoutstanding in its ability. to bring about the above-mentioned crimpingaction under the conditions of our process.

In addition to compounds which are generally found that certain otheragents which may be regarded as solvents or semi-solvents for celluloseacetate and other cellulose organic deriva-- main body of the agententrained therein. Thefilaments, either'before or after they leave thecabinet may, if desired to facilitate winding, be subjected to alubricating treatment. This may be done by conducting the yarn as itemerges from the cabinet through a bath of the lubricant or in contactwith an applicator roll dipping in a lubricant bath. The yarn may thenbe wound on bobbins and stored for future treatment or it may passdirectly to the stapling operation. In either case, a plurality of yarnstrands or threads are warped together to form a high denier rovin of aconvenient size, for example, a roving, of f 1,000,000 denier, thisbeing passed to a stapling regarded specifically as plasticizers, wehave this depending upon tives give highly satisfactory results ascrimping 1 and crinkling agents when employed in accordance with ourinvention. mo those we may mention those aliphatic ketones having aboiling point of over approximately C., such as diethyl ketone, dipropylketone, diamyl ketone,

machine where the filaments are cut to the desired length. In makingso-called short wool type staple we may employ three denier filamentsand cut to a staple length of 2 4 inches, while in making the long wooltype staple. we may employ 5-20 or even 25- denier filaments and cutfrom 4-Iinches. These figures are of course merely 11- L lustrative'aswe may employ filaments of a greater or less denier and cut to otherlengths, the particular type of product required.

, At this point, it may be though themore important aspect of ourinvention is the production of wool type cellulose derivative staple,nevertheless the broad scope of our invention includes theproduction ofa type of methyl isopropyl ketone,methyl isobutyl ketone, methyl ethylketone, methyl amyl ketone, and

diacetone alcohol.- In addition to these-keton c staple somewhatresembling natural cotton fibers. particularly as regards its ability tobe spun into yarn on the cotton system. Broadly well to state that, al-

considered, the cotton type staple produced in accordance with ourprocess differs from the wool type only in "a matter of staple length,the cotton type staple being cut to a length of 14 inches as compared toa length of 2 /2-7 or more inches for the wool type staple.

'After the cutting operation the staple yarn is preferably, although notnecessarily, subjected to a mechanical opening treatment, such as'bysubjecting it to a blast of air or mechanically equivaient treatment.

This mechanicalopening treatment is desirable for the reason that itpermits the crinkling action upon each cut filament to take place withgreater facility and furthermore permits us to, further dry the cutfilaments to remove the residual acetone (some 5 to being containedtherein) from the filaments. This further drying is accomplished bymerely conducting the opened filaments through a'tunnel dryer by meansofa conveyor, the dryer being heated to approximately 105 C. at thehottest point, the hot air being conducted slowly through the dryercountercurrent to the movement of the fibers. The cut staple is thensubjected to the crimping operation per se which consists in subjectingit to the action of a boiling or hot vaporous non-solvent bath. The:bath is preferably first brought to a' action of the crimping agent andthe hot nonsolvent result in imparting a pronounced crimp to each of theindividual fibers. Although a rather wide range of non-solvents may beem-' ployed inor as the crimping bath, we prefer to employ compoundscharacterized by the presence therein of one or more hydroxyl groups,

which compounds, although generally to be regarded as non-solvents,nevertheless presumably have a latent solvent or softening ,action onthe cellulose derivative material of the filaments. In general, monoorpolyhydric alcohols aresuitable. Examples of compounds of this naturewhich we have found particularly satisfactory for the purposes of ourinvention are glycerol, di-

ethylene glycol, amyl alcohol andwater.

The staple may then be removed from the crimping bath and treated togive it antistatic properties by immersion in a suitable antistaticbath. Such baths and the methods of using them are described and claimedinthe copending application of W. T. Jackson and W. (3. Few; Serial No.114,077, filed December 3. 1936 and corresponding to U. S. Patent2,197,930 and the application of J. R. Caldwell, Serial No. 114,085,

filedDecember 3, 1936. The staple after removal from the antistatic bathis dried by any suitable means such as a current of moderately warm airand is'then ready for workingiup on the usual textile machines. f

The crimp imparted to the'staple by the above described process gives ita decided woolly appearance and feel. Not only does the product bear astriking resemblance to natural wool in appearance and feel, but alsopossesses to a high degree the resiliency and kinkiness peculiar to woolfibers. crimp or .kinklness and resiliency of fibers produced inaccordance with our invention is permanent and is not subsequently lostin further processing of "the staple or the spun yarns and fabrics--produced therefrom for the reason that cellulose .organicderivativeshave high tensile strength atatmospheric temperatures and do not timethe resistance .ortne cellulose organic deriv-.

ative fiber to deformation at atmospheric temperature contributes to thefabric an ability to resist mussing' or wrinkling to even a greaterextent than natural wool fabrics.

Another feature or our staple filaments and one which additionallydistinguishes them from any other products of the prior art is the factthat they have a characteristic irregularly rounded, orfpotato-shapedcross-section. Reference to Figs. 4, 5, and 6 of thedrawing illustrating cross-sections of typical crimped staple filamentsproduced in accordance-with our invention will clearly show that thecross-section of each filament is distinguished by the presence of aplurality of rounded cusps projecting from the more or less round mainbody structure of the filaments. It will thus be clear that the crinkledor "crimped appearance of the filaments of our invention is not. due toany effect such as that obtained when flattened or ribbon-likefilarnents are twisted or otherwise mechanically distorted.

As will'be evident mm a consideration of- Figs. 1, 2, mini vtheaecor'npanying drawing, it is a further chaiacteristic *or the staplefibers of our invention that they have, .normally, considerably morethan 11) kinks per inch, and on the average more than 20 kinks per inch,many fibers produced by our invention having as many as 30 taco, or evenmore kinks per inch. It will be observed that these kinks do not occurin one plane-which is every useful characteristic of such fibers.'ihekiriks per inch are easily counted by inspecting the fiber under amicroscope with a black background,- by the use of a one inch field. Thekinks per inch in several fibers (say ten) are and the average taken asrepresentative of the number of kinks per inch of the fibers in thatbatch. Because of the high resistance of fibers to deformation, theresistance of the fiber to loss ofkink when a fiber is placed undertension is quite remarkable, i. e. when a single fiber is p aced undertension, the tension must.

be quite high-relatively-Mfore there is appreciable loss 01 kinkpermanent straightening of the fiber. when our new fibers are made intoa wiring and the roving drawn into a yarn, the yam-'-for the abovereasons-has a tensile 'strengthinexcess of that'of natural wool yarn.

'lhe crimped cut staple fibers herein described are identical in allrespects with the material referred to in our co -pending applicationSerial No. 114,078, filed December 3, 1936, of which the presentapplication is in part a continuation.

Our invention will be more fully understood A It should also be notedthat the by reference to the following examples and description in whichwe have set forth several of the preferred embodiments of our inventionwhich a aasaevv extrusion orifices of about .1 mm. in diameter and inheight, of the type referred to in Stone U. 8. Patent 2,000,048. Thefilaments were spun downwardly at a linear speed of about 330 feet perminute, the filaments passing countercurrently to a body of heated airpassing through the cabinet at a. speed of approximately 23 cubic feetper minute, the air inlet temperature being about 110 C; and the airoutlet temperature being about 78 C. The draft (peripheral roll velocitydivided ments'from a plurality of spinning cabinets to a convergingpoint where the having is formed, the filaments in the rowing being insubstantially parallel relationship to one another. This roving was'thenfed to a. stapling machine of standard construction and cut into staplelengths of Etc 4 inches after which the cut material was opened by meansof pickers and further dried. The staple was then entered into a bath ofboiling water in such amount as to have present in the bath one part byweight of staple to about 30parts by weight of water and boiled for 5 to30 minutes (depending on the extent of crimping desired). removed,centrifuged, and dried in a current of warm air maintained atatemperature of about 95 C.

The resulting product was a cut staple having a high degree of crimp orkinkiness and resiliency,

an irregularly rounded, "potato-shaped" crosssection and closelyresembling natural wool in appearance and physical properties. Theindividual staples possessed a. high degree of luster,notwithstandingthe fact that they had been exposed to merits. A crimped wool-likeproduct was produced.

Example IV .---The procedure of Example I was employed to produceacrimped cut staple, except that about based on the weight of thecellulose acetate, of diamyl ketone was employed in the spirmingdope. Asin the previous examples, a crlmped, woolly product adapted for themanufacture of spun yarns was obtained.

Example V.--A spinning dope was prepared containing 27.3% by weightcellulose acetate propinonate, 7% water and 65.7% acetone. Into thisdope there was incorporated about 1.3% based on the dry weight of thecellulose acetate mounted in a spinning cabinet of about 201 feet p pi me of glycerol tributyrate. This dope after triple filtration was passedto a candle filter maintained at a temperature of 69-'i1 C. and thencethrough a spinneret halving extrusion orifices of about .06-08 mm.indiameter and mounted in a spinning cabinet of about it. in height ofthe type referred to in the Stone Patent 2,000,048. The filaments werespun at a linearspeed of about 300-600 ft. per minute, the filamentspassing countercurrently to a body of heated air passing through thecabinet at a speed of approximately 20-23 cubic feet per minute, the airinlet temperature being about 105 C. and the outlet temperature beingabout 80 C. The draft was 14.7. These spinning'conditions g'ave 9-5denienfllaments;

Yarn from a plurality of cabinets operated as described in the previousparagraph-was fed directly to a, rotary staple cutting machine and cut.to a staple length of'5-7 inches. The cut staple fibers were thenimmersed in a crimp-inducing bath of boiling water and thereaftertreated as described in Example I. As. in the previous examples, theproduct was a crimped, cut staple of ticular case there were about tocrimps .per

inch imparted to the staple.

We may produce a cut staple having even a higher number of crlmps perinch by employing a somewhat higher viscosity cellulose acetate thanwhat is regarded as nornialin the industry.

having as many as 40 or even more crimps per inch.

the action of boiling water which would ordinarily be expected to bringabout marked delustering. About twenty crimps per inch were found tohave been imparted to the staples.

' and resiliency, an irregularly rounded cross-section and closelysimulating natural wool wasproduced.

Example IL-A cut staple cellulose acetate yarn closely resemblingnatural wool was produced by following the procedure of Example I,except that 8% based on the weight of the cellulose scetate, ofdiacetone alcohol was added to the spinning dope prior to extrusion ofthe fila- While the foregoing examples have been based upon the use ofsubstantially boiling water as the non-solvent for our process it hasbeen pointed out elsewhere herein that other non-solvents may beemployed. For instance, instead of water we may employ such non-solventsas glycerol, diethylene glycol. amyl alcohol and the like so long asthey are non-solvents forthe filaments at the temperatures employed,or'at least do not have in a non-solvent liquid we may vaporize thenonsolvent liquid at a temperature of approximately C. and cause thevapors to pass through the cut filaments until the desired is'obtained.

Although we have found it convenient to illustrate our invention byreference to certain specific examples and to certain conditions ofoperation, it will be apparent that many modifications are possiblewithin the scope of our invention. For

crimping action characterized by the presence therein of a high boilingcompound boiling at or above approximately 100 C. J

The amount of the high boiling crimping compound may vary within ratherwide limits, depending, not only upon the particular cellulosederivatives employed in the spinning dope, but also upon the degree andkind of crimping effect desired in the finished staple fiber. Forexample, when employingcellulose acetate or other cellulose organicderivative as the filament material, we may use as little as about 1%,based on the dry weight of the cellulose derivative material, of thecrimping compound. On the other hand, we may employ as much as 25% ormore of the crimping compound. As indicated in Example V, one of themost satisfactory compositions which we have employed for themanufacture of wooltype staple in accordance with our'invention is onecontaining .36 part by weight of plasticizer to 27.3 parts by weight ofcellulose acetate, representing about 1.3% of the plasticizer, based onthe weight of the acetate.

The preferred range for most crimping agents is about 1 to 15%. Ingeneral, it may be said that the higher the concentration of thecrimping agent in the filaments before treatment in the hot crimpingbath, the more intense will be the crimping effect. However, the greaterthe amount of plasticizer the lower will be the tensile strength of thefilaments, and it is therefore a question of balancing the maximum crimpdesired against the minimum decrease in tensile strength permissible. i

Likewise, the temperature of the spinning dope, speed of spinning,temperatures of the evaporative medium in the spinning cabinet, speed ofthe evaporative medium passing through the cabinet, draft and the like,may vary rather widely to meet varying conditions or to meet therequirements of particular types or denier of staple it is desired toproduce. In producing the longer wool type staple it is desirable toemploy a rather high denier yarn. Under such circumstances, the spinningspeed will be relatively lower than the spinning speeds employed for thelower denier staples, and the various conditions of spinning such as airtemperatures, air speed, draft and a other factors will be adjustedaccordingly.

' tive staple which, in its physical properties and appearance and itsability to be woven into spun yarn and employed in the manufacture ofmany different types of textile fabrics is absolutely unique. While wedo not confine ourselves to any particular theory to explain the unusualresults obtained by the process of our invention, it appears that thedevelopment of the characteristic configuration of the staple is due tothe combined action of the high boiling crimping agent employed in thespinning dope and the action of the hot non-solvent thereon. It appearsthat, due to some action of the crimping agent on the cellulosederivative material, the explanation of which is not clearly understood,the filament material is brought into a condition in which thenon-solvent causes it to crimp,

crinkle or, in a sense, shrivel' and assume the characteristic wool'likecondition. This crimping action may conceivably be due to a heterogeneous disposition of the agent in the cellulose derivable materialwhich gives rise to some sort of micellar re-arrangement of thecellulose derivative material such that, under the influence of the hotnon-solvent, certain strains are released, equalized or createdthroughout the body of the filament material. Whatever the explanationmay be, the'crimping action is exclusively induced by the presence inthe interior of the filament-of the crinkling rather than by exclusivelyexternal means. Although, according to our invention the crimping effectis finally induced by the application of an external agent, namely, thehot non-solvent, the desired results are obtained only by employing ahigh boiling compound as an ingredient of the spinning dope as set forthabove. This clearly distinguishes our process from all of the prior artprocesses referred to above, which depend exclusively upon the externalapplication of crimping agents of various kinds or upon the applicationof external molding, stretching or othermechanical forces to the surfaceof the 'fiber. It appears that inducing the crimping action from theinterior of the fiber is the necessary condition for the production of atruly wool-like staple. In any event, the fact remains that until theadvent of the present invention, the prior art has never brought forwarda satisfactory wool substitute, nor so far as we are aware, has anysatisfactory synthetic wool fabric been produced prior to our invention.

A further and definitely distinguishing characteristic of our inventionis the fact that the resiliency, strength and luster of our staplefibers is substantially unefiected by treatment with hot water or othercellulose derivative non-solvent. Quite contrary to what would beexpected by subjecting such plastic material as cellulose acetate, forexample, to the action of hot water, no incipient precipitation withconsequent delustering occurs and the fibers retain their originalluster. In addition, the original strength and resiliency of the fibersis substantially preserved.

Another outstanding characteristic of the wool like staple fibersproduced in accordance with our invention is the fact that the crimpingis permanent and is not removed, either in processing on the varioustypes of textile machinery involved in the manufacture of spun yarns andthe manufacture of such yarns into textile fabrics, or by repeatedwashing in aqueous scour baths. In fact, even after repeated scouring inrelatively strong soap solution, our staple retains its originalwool-like configuration, resiliency, brilliance and luster, and fabricssuch as woo blankets and other fabrics produced from our material may berepeatedly washed and cleansed in accordance with standard launderingpractice without shrinkage or other adverse effect thereon. Furthermore,the material is completely moth-proof, a feature which places fabricsproduced from this type of staple definitely in a class by themselves.

It will be evident from a consideration of the properties of our newwool type staple that it a given blend.

a matter of fact, it is one of the outstanding characteristics of ourproduct that it so nearly simulates natural wool that it may beprocessed in accordance with standard practice and without anyalteration of conditions orequipment. However, we should point out thatour product is in many respects outstandingly superior to natural rawwool, since it may be employed directly in the various processingoperations and spun into yarn without the necessity of removing foreignsubstances which are always present in the natural product. As iswell-known, in the processing of natural wool it losesin some instancesanywhere from to 30% or more of its weight in processing, this lossbeing represented by sticks, burrs, dirt, grease and other foreignsubstances, as well as the combing out of fibers having too short alength to be useful in the manufacture of yarns. The scouring of greasefrom wool requires large machines and considerable labor, adding to thecost of processing; De-burring operations require large machines I orcarbonizing. Either the mechanical or chemical de-burring operations addto the cost'of' processing natural wool. It will be readily understoodthat none of these inherent defects are present in the wool type stapleof our invention;

Not only is it possible to obtain much higher yields of finished productwhen employing our wool type staple than is possible with'the naturalproduct, but 'we are enabled to definitely control the length of thevarious staplesentering into a given yarn product. Whereas natural woolcontains fibers varying in length, our product can be producedso thatall of the staples are of substantially equal length and denier.However, and as is well-known it is desirable to employ a blend ofdifferent staples for the production of various types of spun yarn. Forinstance, it may be desired to use a mixture of short and long staples.In such a. case, we may use a mixture of wool type staples varying inlength all the way from about three inches to about seven ment denier-itis easily possible to duplicate the a real wool blends now commonlyemployed'in the production of wool yarns.

The wool type cellulose derivative staples of our invention may, asindicated above, be employed in the manufacture of spun yarn and alsoyarns employed for ordinary knitting purposes. These spun yarns may beemployed in the manufacture of suitings, blankets, and many other typesof fabrics. One of the most important uses of our product is in themanufacture of. mohair. In fact, our product may be employed as asubstitute for all or part of the natural wool now employed in makingthis type of fabric.

aasaevv ployed or vice versa. All of the above types and combinations ofyarns andfabrics are included within the scope of our invention. Inusing both the composite yarn and the type of cloth eonstruction justreferred to, numerous attractive cross-dyeing effects may be obtained.

It will thus be apparent that our invention represents an outstandingadvance in the art of producing artificial textile materials, especiallyin that it enormously extends the field of applica tion of celluloseorganic derivative filaments. In

fact, our work leads us to the conclusion that the wool type stapleproduced in accordance with our invention may be employed in practicallyall cases where natural wool fibers are now used. Not only is ourmaterial a practical substitute for natural wool, but in many respectsit is vastly superior thereto, especially as regards its luster,brilliance, purity and other characteristics.

What we claim is:

1. The method of making crimped cellulose organic derivative cut staplefibers having a high resiliency and capable, when fabricated intotextile products, of retaining their resiliency and crimp under normalconditions of use resembling that of natural wool, which comprisesforming filaments of irregularly rounded cross-section from a celluloseorganic derivative dope containing a glycerol ester of an aliphatic acidhaving three to four carbon atoms, removing the solvent from a celluloseacetate dope containing a glycerol ester of an aliphatic acid havingthree to four carbon atoms, removing the solvent therefrom butsubstantially retaining the glycerol ester therein, cutting thefilaments into staple lengths and subjecting the cut staples to theaction of boiling water.

3. The method. of making crimped cellulose organic derivative cut staplefibers having a high I resiliency and capable when fabricated intotextile products, of retaining their resiliency and crimp under normalconditions of use resembling that of natural wool, which comprises Ourwool type staple may also be employed in the manufacture of so-calledmixed or composite.

yarns by mixing the wool type staple with cotton, silk, natural wool orother types of textile fibers and spinning in the usual manner. Yarnsspun wholly or partly from our product may also formingfilaments ofirregularly rounded crosssection from a cellulose organic derivativedope containing glycerol tributyrate, removing the solvent therefrom butsubstantiallyretaining the glycerol tributyrate therein, cutting thefilaments into'staple'lengths and subjecting the out staples to theaction of boiling water.

natural wool, which comprises formingfilaments of irregularlyroundedcross-section from a cellulose acetate dope containing glyceroltributyrate. removing the solvent therefrom butsubstantially retainingthe glycerol trlbutyrate therein, cutting the filaments into staplelengths and subjectin the cut staples to the action of boiling water.

5. The method of making, crimped cellulose organic derivative cut staplefibers having ahigh filaments having more than-ten crlmps per inch spasmresiliency andoapable, when fabricated into textile products, ofretaining their resiliency and crimp under normal conditions of useresembling that of. natural wool which comprises forming filaments ofirregularly rounded cross-section from a cellulose organic derivativedope containing glycerol triproplonate, removing the solvent therefrombut retaining the glycerol tripropionate therein, cutting the filamentsinto staple lengths 1 and subjecting the out staples to the action ofboiling water.

6. The method of making crimped cellulose V acetate cut staple fibershaving a high resiliency and apable, when fabricated into textileprodnets, of retainingtheir resiliency and crimp under normal conditionsof use resembling that of natural wool which comprises forming filamentsof irregularly rounded cross-section from a cellulose acetate dopecontaining glycerol tripropionate, removing the solvent therefrom butretaining the glycerol .triproplonate therein. cutting the filamentsinto staple lengths and subjecting the cut staples to the action ofboiling water.

7. Permanently crimped synthetic staple fibers of high resiliencyconsisting of relatively short filamentscomposed of a cellulose organicderivative containing a glycerol ester-of an aliphatic acid having threeto four carbon atoms, said of filament length and an irregularly roundedcross section and capable, 'when fabricated into textile products, ofretaining their original resiliency under normal conditions of use.-

8. Permanently crimped Synthetic staple fibersi 35oihighresiliency-consistingofrelativelyshortl filaments composed of acellulose organic deriva tive containing tributyrin, said filamentshaving more than ten crimps per inch of filament length and an irreularly rounded cross section and capable, whenfabricated into textileproducts, of retaining their original resiliency under normal conditionsof use.

9. Permanently crimped synthetic staple fibers of high resiliencyconsisting of relatively short filaments composed of a cellulose organicderivative containing tripropionin, said filaments having more than tencrimp: per inch of filament length and an irregularly rounded crosssection and capable, when fabricated into textile products, of retainingtheir original resiliency under normal conditions 01' l0. Permanentlycrimped synthetic staple fibers of high resiliency consisting ofrelatively short filaments composed of cellulose acetate and anirregularly rounded cross section'andcapable. when fabricated intotextile products, a

of retaining their original resiliency under nor-' containin tributyrin,said filaments having more than ten crimps per inch or filament lengthand an irregularly rounded cross section and capable. when fabricatedinto textile products, of retaining their original resiliency undernormal condi-:

tions of use.

1i. Permanently crimped synthetic staple fibers or high resiliencyconsisting of relatively short filaments composed of cellulose acetatecontaining tripropionin, said filaments having more than ten crimps perinch of filament length mal conditions of use. 1

WALLACE '1, JACKSON. HENRY R. CHILDB.

